1. Field
This invention relates to an apparatus for the external fixation and stabilization of a fractured bone and, more particularly, to such apparatus having enhanced adjustability for precise pin placement.
2. Description of the Prior Art
External fixation devices have been utilized for a number of years for setting and stabilizing fractured bones. While fixator devices and systems have undergone considerable evolutionary changes over the years, they all consist essentially of means for rigidly holding the sections of a broken bone in alignment throughout the healing process. Such apparatus may comprise a relatively crude splint or cast, or may comprise a more modern and sophisticated system involving surgical pins secured to an external fixator bar, or the Ilizarov system well known to those skilled in the art.
A common fixator systems currently on the market comprises a hexagonal fixator bar used to interconnect and rigidly secure a plurality of surgical pins inserted into the fractured bone at various points, with each surgical pin being retained within a clamp secured to the hexagonal bar. Each clamp is installed onto the hexagonal bar by sliding the clamp over one end or the other and tightening one or more nuts when the clamp is in its desired longitudinal position on the bar. Each clamp holds at least one pin at a fixed angle relative to the clamp, with all pin movement at any given longitudinal clamp location being constrained within a plane at rights angles to the bar. When pin clamps having multiple pins are employed, all pins within a single clamp are confined to the same alignment without any freedom for independent placement.
A number of significant problems with the above described fixator system have become evident to those skilled in the art. Placement of the surgical pins in a fractured bone is always a concern to the surgeon and, in some cases, may be of critical importance. With the above described system, optimal adjustment of a clamp for precise pin placement can be extremely difficult and time consuming, under circumstances where time is at a premium. In certain situations, optimal placement of all pins is impossible due to the nominal adjustment capabilities of the pins relative to the clamps.
Several efforts have been made to improve the adjustability of external fixators, including the devices shown in French Patent No. 2,499,400, issued Aug. 13, 1982 to Tornier, European Patent Application No. 490,812, published Jun. 17, 1992 to Mata, et al., U.S. Pat. Nos. 4,273,116, issued Jun. 16, 1981 to Chiquet, 4,620,533, issued Nov. 4, 1986 to Mears, 4,895,141, issued Jan. 23, 1990 to Koeneman, et al., 4,693,240, issued Sep. 15, 1987 to Evans, and 4,299,212, issued Nov. 10, 1981 to Goudfrooy. The inventions shown in each of these references have proven to be either too cumbersome to use and/or insufficiently effective to warrant the additional cost and trouble.
In light of the above described prior art and problems associated therewith, a significant need has arisen for a relatively simple external fixator having multiple degrees of adjustability that is easy to use and provides a wide range of pin orientations and positions.